Marko Bursic

You didn't mention about a neutralization before, so you need to explain further. Maybe you will need a third loop and extra pH meter if you want a stable loop.

The gold rule of designing cascade loops is to add a regulator for each section as soon as possible. If a third process takes place like a neutralization, then add a new pH meter inorder to control pH in 1st box as quick as possible.

But more comment about what you want to calculate

Could you explain what kind of feedforward did you use? What was the final version of your regulation loop?

RangO

i have make a library for a PID cascade look in my web site... blog.ranghetto.com